Synchronization is a key technology in a communications system, especially in a wireless communications system. Whether a receiver can be efficiently synchronized with a transmitter greatly affects performance of a communications system. Main indicators for weighing synchronization between devices in a communications system are complexity of synchronization implementation and performance of synchronization detection.
A device to device (D2D) communications system and a typical cellular mobile communications system such as the Global System for Mobile Communications (GSM) have a significant difference in terms of synchronization. In the D2D communications system, multiple user equipments (UE) that serve as transmitters may be totally different in timing, and UE that serves as a receiver needs to be synchronized with the different transmitting UEs, to receive signals from the multiple transmitting UEs. Therefore, the communications system imposes a higher requirement on synchronization, and the receiving UE needs to be quickly and effectively synchronized with all transmitting UEs.
In a process of research on standardization of the 3rd Generation Partnership Project (3GPP), a D2D synchronization signal (D2DSS) is introduced to implement synchronization between different D2D transceivers. The D2DSS includes a primary D2D synchronization signal (PD2DSS) and a secondary D2D synchronization signal (SD2DSS), where the PD2DSS implements initial timing and frequency synchronization between a transmitter and a receiver, and the SD2DSS implements fine synchronization. At the present stage, how to generate a synchronization signal with good correlation attracts much attention.